The present invention relates to portable spray units, and more particularly to powered sprayers capable of producing a foam spray.
Portable spray units are used in a wide variety of applications for applying a broad range of liquids. A non-exhaustive list of applications includes: agricultural (pesticides, herbicides, germicides), chemical and janitorial (degreasers, disinfectants, carpet treatments, cleaners, etc.) applications. These sprayers are available in a variety of types. For example, there is a significant market for hand sprayers, which are intended for use in relatively small applications. Typically, hand sprayers are carried by the user and operate through a manually-actuated hand-pump. There is also a significant market for larger sprayers, which typically provide greater delivery rates and improved performance for larger applications. Large commercial sprayers are typically operated through an external supply of compressed air, for example, from an external, stand-alone compressor. In operation, compressed air is supplied to the tank to place the liquid under pressure, and this pressure is used to expel the liquid from the tank.
For many sprayer applications, it is desirable for the spray to be a foamy, heterogeneous mixture of gas and liquid, as opposed to a homogeneous liquid. Possible examples here include the application of pesticides, herbicides, cleaners, etc. There are a variety of advantages to a foamy spray. For example, the consistency of the foam is generally greater than that of a pure liquid, and will thus remain on the applied area for a longer period of time, being less likely to experience run-off. Further, the opaque foam provides a visual indicator to the user as to which areas have already been treated and which have not. Without these properties, there are two possible negative consequences. First, the user may potentially under-apply the spray inasmuch as certain areas might receive no liquid whatsoever and/or the contact time of the liquid with the applied area might be insufficient due to run-off. An alternate possibility is that the user, in an attempt to compensate for the previous drawback, may consistently over-apply the spray. This is an economic disadvantage from the standpoint of greater product consumption, and also possibly a health and/or environmental risk if the applied chemical is hazardous.
There are a variety of commercially available portable, hand-operated foaming sprayers. Perhaps the most effective portable, hand-operated foaming portable sprayer on the market is available from Innovative Cleaning Equipment of Grand Rapids, Mich., under the FOAM-IT trademark. This unit provides highly consistent and readily adjustable foam effluent from a broad range of liquids. The unit also includes a variety of adjustments that permit the characteristics of the effluent to precisely controlled. Despite these benefits, the portable, hand-operated foaming sprayer is not ideal for all applications. In larger applications, it may be desirable to power the spray unit so that the user is not required to repeatedly charge the tank through operation of a hand pump. Further, in larger applications, the standard tank provided with the hand unit may be smaller than desired and therefore require repeated refilling.
As a result, there is a need for an improved powered portable sprayer that can effectively provide higher flow rates while at the same time provide foam of consistent composition and sufficient expansion ratios.